client/src/emv/emv_roca.c

   1 /* roca.c - ROCA (CVE-2017-15361) fingerprint checker.
   2  * Written by Rob Stradling (based on https://github.com/crocs-muni/roca/blob/master/roca/detect.py)
   3  * Copyright (C) 2017-2018 Sectigo Limited
   4  * modified 2018 iceman  (dropped openssl bignum,  now use mbedtls lib)
   5  * modified 2018 merlok
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation, either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20 //-----------------------------------------------------------------------------
  21 // EMV roca commands
  22 //-----------------------------------------------------------------------------
  23
  24 #include "emv_roca.h"
  25
  26 #include "ui.h"  // Print...
  27 #include "bignum.h"
  28
  29 static void rocacheck_init(mbedtls_mpi *prints) {
  30
  31     for (int i = 0; i < ROCA_PRINTS_LENGTH; i++)
  32         mbedtls_mpi_init(&prints[i]);
  33
  34     mbedtls_mpi_read_string(&prints[0], 10, "1026");
  35     mbedtls_mpi_read_string(&prints[1], 10, "5658");
  36     mbedtls_mpi_read_string(&prints[2], 10, "107286");
  37     mbedtls_mpi_read_string(&prints[3], 10, "199410");
  38     mbedtls_mpi_read_string(&prints[4], 10, "67109890");
  39     mbedtls_mpi_read_string(&prints[5], 10, "5310023542746834");
  40     mbedtls_mpi_read_string(&prints[6], 10, "1455791217086302986");
  41     mbedtls_mpi_read_string(&prints[7], 10, "20052041432995567486");
  42     mbedtls_mpi_read_string(&prints[8], 10, "6041388139249378920330");
  43     mbedtls_mpi_read_string(&prints[9], 10, "207530445072488465666");
  44     mbedtls_mpi_read_string(&prints[10], 10, "79228162521181866724264247298");
  45     mbedtls_mpi_read_string(&prints[11], 10, "1760368345969468176824550810518");
  46     mbedtls_mpi_read_string(&prints[12], 10, "50079290986288516948354744811034");
  47     mbedtls_mpi_read_string(&prints[13], 10, "473022961816146413042658758988474");
  48     mbedtls_mpi_read_string(&prints[14], 10, "144390480366845522447407333004847678774");
  49     mbedtls_mpi_read_string(&prints[15], 10, "1800793591454480341970779146165214289059119882");
  50     mbedtls_mpi_read_string(&prints[16], 10, "126304807362733370595828809000324029340048915994");
  51 }
  52
  53 static void rocacheck_cleanup(mbedtls_mpi *prints) {
  54     for (int i = 0; i < ROCA_PRINTS_LENGTH; i++)
  55         mbedtls_mpi_free(&prints[i]);
  56 }
  57
  58 static int bitand_is_zero(mbedtls_mpi *a, mbedtls_mpi *b) {
  59
  60     for (int i = 0; i < mbedtls_mpi_bitlen(a); i++) {
  61
  62         if (mbedtls_mpi_get_bit(a, i) && mbedtls_mpi_get_bit(b, i))
  63             return 0;
  64     }
  65     return 1;
  66 }
  67
  68
  69 static mbedtls_mpi_uint mpi_get_uint(const mbedtls_mpi *X) {
  70
  71     if (X->n == 1 && X->s > 0) {
  72         return X->p[0];
  73     }
  74
  75     PrintAndLogEx(WARNING, "ZERRRRO!!!\n");
  76     return 0;
  77 }
  78
  79 /*
  80 static void print_mpi(const char *msg, int radix, const mbedtls_mpi *X) {
  81
  82     char Xchar[400] = {0};
  83     size_t len = 0;
  84
  85     mbedtls_mpi_write_string(X, radix, Xchar, sizeof(Xchar), &len);
  86     PrintAndLogEx(INFO, "%s[%zu] %s\n", msg, len, Xchar);
  87 }
  88 */
  89 bool emv_rocacheck(const unsigned char *buf, size_t buflen, bool verbose) {
  90
  91     mbedtls_mpi t_modulus;
  92     mbedtls_mpi_init(&t_modulus);
  93
  94     bool ret = false;
  95     mbedtls_mpi prints[ROCA_PRINTS_LENGTH];
  96     uint8_t primes[ROCA_PRINTS_LENGTH] = {
  97         11, 13, 17, 19, 37, 53, 61, 71, 73, 79, 97, 103, 107, 109, 127, 151, 157
  98     };
  99
 100     rocacheck_init(prints);
 101
 102     MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&t_modulus, buf, buflen));
 103
 104     for (int i = 0; i < ROCA_PRINTS_LENGTH; i++) {
 105
 106         mbedtls_mpi t_temp;
 107         mbedtls_mpi t_prime;
 108         mbedtls_mpi g_one;
 109
 110         mbedtls_mpi_init(&t_temp);
 111         mbedtls_mpi_init(&t_prime);
 112         mbedtls_mpi_init(&g_one);
 113
 114         MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&g_one, 10, "1"));
 115
 116         MBEDTLS_MPI_CHK(mbedtls_mpi_add_int(&t_prime, &t_prime, primes[i]));
 117
 118         MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&t_temp, &t_modulus, &t_prime));
 119
 120         MBEDTLS_MPI_CHK(mbedtls_mpi_shift_l(&g_one, mpi_get_uint(&t_temp)));
 121
 122         mbedtls_mpi_free(&t_temp);
 123         mbedtls_mpi_free(&t_prime);
 124
 125         if (bitand_is_zero(&g_one, &prints[i])) {
 126             if (verbose) {
 127                 PrintAndLogEx(FAILED, "No fingerprint found.\n");
 128             }
 129             mbedtls_mpi_free(&g_one);
 130             goto cleanup;
 131         }
 132         mbedtls_mpi_free(&g_one);
 133     }
 134
 135     ret = true;
 136     if (verbose)
 137         PrintAndLogEx(SUCCESS, "Fingerprint found!\n");
 138
 139 cleanup:
 140     mbedtls_mpi_free(&t_modulus);
 141
 142     rocacheck_cleanup(prints);
 143     return ret;
 144 }
 145
 146 int roca_self_test(void) {
 147     PrintAndLogEx(NORMAL, "");
 148     PrintAndLogEx(INFO, "ROCA check vulnerability tests");
 149
 150     // positive
 151     uint8_t keyp[] = "\x94\x4e\x13\x20\x8a\x28\x0c\x37\xef\xc3\x1c\x31\x14\x48\x5e\x59"\
 152                      "\x01\x92\xad\xbb\x8e\x11\xc8\x7c\xad\x60\xcd\xef\x00\x37\xce\x99"\
 153                      "\x27\x83\x30\xd3\xf4\x71\xa2\x53\x8f\xa6\x67\x80\x2e\xd2\xa3\xc4"\
 154                      "\x4a\x8b\x7d\xea\x82\x6e\x88\x8d\x0a\xa3\x41\xfd\x66\x4f\x7f\xa7";
 155
 156     int ret = 0;
 157     if (emv_rocacheck(keyp, 64, false)) {
 158         PrintAndLogEx(SUCCESS, "Weak modulus   [ %s ]", _GREEN_("PASS"));
 159     } else {
 160         ret++;
 161         PrintAndLogEx(FAILED, "Weak modulus   [ %s ]", _RED_("Fail"));
 162     }
 163
 164     // negative
 165     uint8_t keyn[] = "\x84\x4e\x13\x20\x8a\x28\x0c\x37\xef\xc3\x1c\x31\x14\x48\x5e\x59"\
 166                      "\x01\x92\xad\xbb\x8e\x11\xc8\x7c\xad\x60\xcd\xef\x00\x37\xce\x99"\
 167                      "\x27\x83\x30\xd3\xf4\x71\xa2\x53\x8f\xa6\x67\x80\x2e\xd2\xa3\xc4"\
 168                      "\x4a\x8b\x7d\xea\x82\x6e\x88\x8d\x0a\xa3\x41\xfd\x66\x4f\x7f\xa7";
 169
 170     if (emv_rocacheck(keyn, 64, false)) {
 171         ret++;
 172         PrintAndLogEx(FAILED, "Strong modulus [ %s ]", _RED_("Fail"));
 173     } else {
 174         PrintAndLogEx(SUCCESS, "Strong modulus [ %s ]", _GREEN_("PASS"));
 175     }
 176     return ret;
 177 }